There is a problem with geoffrey-kolbe's calculator.

[quyang]

geoffrey-kolbe has developed a very good elastic calculation software. Although the author has rich experience and technical ability. But consider that he was not specifically developed for the subsonic range. A major problem was found in the calculation of this software.
    In the field of sub-tones, a spring type designed by this software has a stability coefficient of 1.6 in theory. This bullet type is 0.7 times the diameter of the flat head meplate. However, in the actual experiment, it was found that the speed of this bullet type 240/M was in an excessive rotation state, and the best accuracy was achieved until the initial speed was reduced to about 180/M, and the speed range with accuracy was narrow and the accuracy was unstable. Another large arc head (similar to the old rifle warhead) with a stability factor of 1.2 verified by this software has insufficient rotation.
    Experiments show that this software is inaccurate for MEPLATE projectiles with larger diameters at subsonic speed.
    It is proved by experiments that this software is inaccurate in calculating the arc-head projectile at subsonic speed.
    At present, it is found that the calculation is accurate for the no-tail boat and the pointed projectile.